The phrase 'national treasure' gets bandied about a bit too much these days, but June Brown is surely deserving of the title.

Since first setting foot in Albert Square back in 1985, her soap alter ego Dot Cotton has been as synonymous with EastEnders as the 'doof doof doofs' at the end of each episode; appearing in a puff of cigarette smoke to offer a doleful look, Biblical quote or a crushing judgement.

As Brown approaches her 90th birthday, the BBC is honouring the veteran star with a special documentary, June Brown At 90 - A Walford Legend. Viewers can look forward to a candid interview with the actress herself, and contributions from Walford regulars, including Lacey Turner, Adam Woodyatt and Natalie Cassidy.

Here's a look back on the star's eventful life and career so far...

June Brown at 90

EARLY YEARS

Brown was born in Suffolk on February 16, 1927. She served in the Wrens (Women's Royal Naval Service) at the end of the war before joining drama school. She was trained by the likes of Laurence Olivier at the Old Vic Theatre School, and appeared on stage alongside Sir John Gielgud.

More theatre roles followed. After seeing her in a performance as Henrik Ibsen's Hedda Gabler, the Yes Minister actor Nigel Hawthorne reportedly described her as "one of the most beautiful creatures I've seen on stage".

FAMILY LIFE

June Brown at 90

Brown's life hasn't been without tragedy. Her younger brother died as a baby, while her elder sister Marise died aged eight. At drama school, she met John Garley, who she married in 1950. He suffered from depression and died from suicide seven years later. Her second husband, Robert Arnold, was also an actor, and the couple were married for 45 years before his death in 2003.

Brown and Arnold brought up five children together - a sixth, their daughter Chloe, was born prematurely and died at 16 days old. But despite the heartache, Brown has revealed: "I can't say my life has been dominated by tragedy. I refuse to accept that. I've had less than some, more than others."

[Read more: I had more love affairs than Dot, reveals June Brown]

COTTONING ON

June Brown at 90

By the time she landed her role in EastEnders, Brown was in her late-50s, and a well-established theatre, film and TV actress. In fact, long before Walford came knocking, Brown had appeared in several episodes of rival soap Coronation Street. She played Mrs Parsons, the mother of Tony, in 1970 and 1971.

It was Leslie Grantham, who played Dirty Den, who suggested her for the role of Dot, a God-fearing hypochondriac who was always trying get her wayward son Nick (John Altman) back on the straight and narrow. Despite only being given a three-month contract initially, after just six weeks, the character was such a success that Brown was asked to become permanent.

The role couldn't have come at a better time for the actress (who took a break from the show between 1993 and 1997); she's admitted she felt her career was "vanishing" in the year before she joined the cast.

It also helped that the chain-smoking launderette worker was such good fun to play. "I could have played Dot as a very dreary woman with a list of illnesses, but I played her with an edge, so it was funny," Brown has said.

DOUBLE ACTS

June Brown at 90

Dot's had some wonderful on-screen pairings during her time on EastEnders - with Altman, who has described her as like a second mother off-screen, Gretchen Franklin, who played Dot's great friend Ethel Skinner, and John Bardon, who played Dot's husband Jim Branning.

One young fan was so convinced by Dot's loyalty to Nick that she wrote to Brown, saying she wanted to come and live with her, "because Dot always stuck up for her son", the actress has revealed.

But perhaps the most eyebrow-raising coupling of Brown's career to date has been with global pop superstar Lady Gaga. The pair appeared alongside each other on The Graham Norton Show in 2013 and got along famously, with Gaga pinning Brown's dress for her, wearing the actress' autobiography as a 'hat', and declaring, "I'm just kind of sad, because I can't take June home with me".

The pair later enjoyed afternoon tea together at Gaga's London hotel.

A TROPHY EPISODE

Dot Cotton in EastEnders

In 2009, Brown carried an entire episode of EastEnders, with Dot dictating a 30-minute monologue to husband Jim into a tape recorder. Jim had suffered a stroke on the show - made all the more poignant because actor Bardon had also suffered one in real life.

Brown's striking, pared back performance was nominated for a Bafta Television Award. She lost out to Anna Maxwell Martin, but has said: "You've got to laugh in the face of disappointment". The actress and her granddaughter fashioned their own version of the award - the Nafta - out of tin foil and a cigarette. It takes pride of place with other Baftas in a BBC awards cabinet.

June Brown At 90 - A Walford Legend airs on BBC One on Thursday, February 16.

Catch up on BBC iPlayer and BT TV Catch-Up.

[Read more: 30 years of Dot Cotton - A look back at the greatest EastEnders moments for June Brown]